1. Field of the Invention
Embodiments of the invention relate to a semiconductor device fabrication method. More particularly, embodiments of the invention relate to a method of forming a small pitch pattern using double spacers.
This application claims the benefit of Korean Patent Application No. 2005-0033205 filed on Apr. 21, 2005, the subject matter of which is hereby incorporated by reference in its entirety.
2. Description of the Related Art
The fabrication of a semiconductor device requires the application of multiple individual processes such as lithography, material deposition, patterning, etching, cleaning, etc. As contemporary semiconductor devices increase in their constituent element densities, design rules for the layout of such elements have become increasingly small and very strict in their tolerances. Reduced design rules result in increasingly small pitch definitions for patterns used, for example, in lithography processes adapted to the fabrication of semiconductor devices. Such reduced design rules and reduced pattern pitches are beginning to challenge the resolution accuracy of conventional lithography equipment. Indeed, some contemporary design rules require resolution beyond that reasonably provided by some conventional.
For example, in one conventional lithography process adapted to the formation of a small pitch pattern of about 50 nm, an ArF immersion lithography technique is commonly used. This technique uses an ArF light source having a wavelength of 193 nm. Alternatively, a lithography process using a F2 excimer laser having a shorter wavelength of 153 nm may ultimately be used, but this technique remains under development and has proved difficult to use in the formation patterns on a semiconductor substrate.
Thus, as a practical matter, lithography technology using a light source having a significantly longer wavelength, (e.g., lithography technology using a light source formed from a KrF excimer laser having a 248 nm wavelength) must still be used. Such equipment is, without successful adaptation, ill-suited to the formation of smaller pitch patterns, such as those having a pitch of about 50 nm or less. In particular, requirements exist for the developing of methods adapted to the formation of small pitch patterns of repeated lines and spaces using conventionally available lithography equipment such as the KrF excimer laser having a 248 nm wavelength as a light source.